The present invention relates generally to the field of automotive airbags, and more particularly to the field of proximity suppression systems for automotive air bags.
Airbags are common safety features in many modern automotive vehicles. While airbags often are effective in protecting vehicle occupants during a crash, they have sometimes been argued to be potentially detrimental to children or other vehicle occupants who sit relatively close to the airbag door (normally installed inside of the vehicle steering wheel or dashboard). One argued potential cause of injuries is that most current airbags deploy with a certain predetermined amount of force. While the predetermined amount of force may be appropriate for most vehicle occupants, it may arguably be too great for children or other relatively small vehicle passengers who sit close to the vehicle dashboard. Airbags have also been argued to be potentially detrimental on occasion when the airbag is deployed and the vehicle passenger is not wearing a seatbelt. In such cases, the force of the vehicle deceleration is argued to cause the unbelted passenger to move too close to the airbag. To address these perceived problems, there have been efforts in the airbag industry to develop proximity suppression systems, which, based on various factors, either suppress the airbag deployment entirely or adjust the force with which it is deployed during a vehicle crash situation. Relatively advanced types of proximity suppression systems include Dynamic Proximity Suppression (xe2x80x9cDPSxe2x80x9d) systems, which sense the nature of a vehicle occupant""s movement toward the airbag during pre-impact deceleration of the vehicle and cause the airbag deployment to be adjusted based on such movement.
DPS systems include a sensing device to detect when a passenger moves into the xe2x80x9csuppression zone.xe2x80x9d The xe2x80x9csuppression zonexe2x80x9d is a defined space in front of the vehicle steering wheel or dashboard into which the airbag deploys. The particular size and shape of the suppression zone depends on the specific airbag being used, the size and configuration of the vehicle""s interior space, and the age and size of the vehicle passenger. FIG. 1 generally illustrates a passenger vehicle and a sample suppression zone 103 for a given airbag. Various DPS sensors detect when the vehicle passenger enters the suppression zone using a variety of methods. One system uses mathematical algorithms to estimate the time at which the vehicle occupant crosses into the suppression zone. Other methods may simply monitor the edge of the suppression zone and detect when the vehicle occupant has crossed over it. Regardless of the particular method used by the DPS system, an electronic airbag controller may suppress or adjust the deployment of the airbag upon impact based on the output of the DPS sensor.
These new DPS sensors require extensive testing before being approved for production. In particular, it is desirable to be able to measure the accuracy of the DPS sensor in determining when the vehicle occupant enters the suppression zone. DPS sensors that use mathematical algorithms to estimate when the vehicle occupant enters the suppression zone have a certain range of error associated with such estimations. Similarly, other types of DPS sensors may have certain lag times between the time when the vehicle occupant actually enters the suppression zone and when the DPS sensor detects such intrusion. In any event, it is desirable to be able to determine and evaluate these estimation errors and lag times. Further, for testing purposes, it is desirable to detect and identify the position of the vehicle passenger relative to the vehicle interior at the time when the DPS sensor detects suppression zone intrusion. A comparison of the actual suppression zone boundary relative to the position of the passenger at the time when the DPS sensor detects suppression zone intrusion is another measure of the accuracy of the DPS sensor.
Traditional vehicle testing methods would require that a vehicle sled test facility be used to simulate a pre-impact deceleration of the vehicle to evaluate the performance of a DPS sensor. The inventors hereof have recognized that it would be useful to have a flexible and accurate system and method for testing DPS sensors that would not require a vehicle sled test facility.
The invention relates to a testing system and method for testing airbag proximity suppression systems, and in particular, dynamic proximity suppression systems. The testing system includes a positioning system for moving an occupant modelxe2x80x94an anthropomorphic dummy or any other geometric shape that substitutes for a human passengerxe2x80x94inside of a vehicle and toward the suppression zone. In a preferred embodiment of the invention, the positioning system generally comprises three perpendicularly-arranged rails that slide relative to each other to facilitate three-dimensional movement of the occupant model. The positioning system is controlled by an electronic controller, which is preferably a personal computer. A high-speed proximity detector monitors movement of the occupant model and produces a first output signal indicative of the point in time when the occupant model actually moves into the suppression zone. The DPS system, the device under test (DUT), provides a second output signal indicative of when the DPS system recognizes that the occupant model has entered the suppression zone. Based on a comparison of the first and second output signals, the electronic controller determines an error value or response time of the DPS sensor as well as the position of the occupant model at the time when the DPS sensor detects suppression zone intrusion. The error value and position information are performance factors that can be used to evaluate the performance level of the DPS sensor.